In the structure of a hybrid-drive wind turbine, the rotating speed of wind wheel is increased to certain times larger by a gearbox and then is input to a generator (e.g., a permanent magnet generator). Essentially, a speed-up gearbox is additionally installed onto a direct-driven wind power generator. Through gear transmission, the hybrid-drive wind turbine increases the rotating speed input from a hub by about 25-40 times, for example, and the both the size and weight of the generator can be greatly reduced as compared to the direct-driven wind power generator. Therefore, the hybrid-drive wind turbine not only has the following advantages existing in the direct-driven wind turbine, such as making it easy to realize low-voltage passing through, being free of high-speed output shaft that is prone to failures, removing failure points such as electric brush, slip or the like from the motor, having a small impact on the power grid, outputting high-quality electrical energy, but also the hybrid-drive wind turbine can effectively avoid disadvantages such as high cost and difficult in hoisting caused by a large direct-driven wind power generator.
Meanwhile, all the current large wind power generators have requirements on lightweight, high integration and high reliability so as to reduce electricity cost. The characteristics of hybrid-drive wind turbines are particularly suitable for large wind machines, and thus have a bright prospect of development.
Currently, a transmission chain of hybrid-drive wind turbine and a gearbox used for the transmission chain typically use a conventional two stage NGW solution, which uses too many elements and has a complicated structure, thus making the processing and assembling difficult; in an existing transmission chain based on NGW solution, all the planet gears receive loads at both faces, thus increasing the possibility of gear failure; moreover, the planet gears rotate, thus increasing the complexity in lubricating solution.
Chinese patent application for invention with publication No. CN101846155A and title “a megawatt scale quasi planet gear hybrid-drive wind turbine speed-up gearbox” discloses a megawatt scale quasi planet gear hybrid-drive wind turbine speed-up gearbox which is easy to assemble and disassemble, can be repaired inside nacelles, has a light weight and a low difficulty in manufacturing process. This patent application uses such a “(input) inner ring gear-two second intermediate gears-quasi planet gear-intermediate gear-(output) center gear” single stage quasi planet structure which conducts two shunts in one plane. Due to the addition of two intermediate gears, such a hybrid-drive wind turbine speed-up gearbox structure results in a two-time shunt, and the load bearing capability can therefore be significantly improved. Meanwhile, due to the single stage transmission, the axial length is short, and the required installation space is small; however, it is obvious that the hybrid-drive wind turbine speed-up gearbox of this patent application has a disadvantage of low transmission ratio and thus cannot meet requirements imposed by high power wind turbines.